Effect of TiO2 Crystal Phase and Preparation Method on the Catalytic Performance of Au/TiO2 for CO Oxidation

Titania-supported gold nanoparticles exhibit excellent low-temperature carbon monoxide (CO) oxidation activity, which is sensitive to the structure of the TiO ₂ support and the preparation method. In this paper, gold catalysts were prepared on TiO ₂ with different anatase-to-rutile ratios by the deposition-precipitation method (Au/TiO ₂ -C) and plasma-assisted deposition-precipitation method (Au/TiO ₂ -PC). The highest performance for CO oxidation was obtained over Au/TiO ₂ for an anatase-to-rutile ratio of 4:6, which may be ascribed to the phase transformation mechanism of TiO ₂ and the preferential deposition of Au nanoparticles on rutile TiO2 in the deposition-precipitation process. Therefore, enlarged contact surface between the Au nanoparticles and the TiO ₂ support was obtained, and more oxygen vacancies may be formed, which are beneficial to CO oxidation. Interestingly, compared with Au/TiO ₂ -C, Au/TiO ₂ -PC exhibited enhanced CO oxidation activity. For example, the reaction rate (ξ) at 30 °C for CO oxidation over Au/TiO ₂ -PC was about 5.8 times greater than that over Au/TiO ₂ -C for an anatase-to-rutile ratio of about 4:6, which was primarily caused by the more active gold species on the surface of TiO ₂ support in Au/TiO ₂ -PC due to the Coulomb interaction during plasma preparation.